1. Area of the Art
The present invention is in the field of thermal barrier coatings used to protect machine parts, in particular engine components subjected to high temperature and corrosive atmospheres.
2. Description of the Prior Art
Many important machine parts-especially turbine engine parts-are exposed to high temperatures and corrosive atmospheres. It is necessary to provide some type of coating to protect these parts from premature wear and erosive or corrosive damage. These coatings are needed both for thermal insulation and environmental protection of engine and similar components. Different types of materials require different types of barrier coatings. Currently, thermal barrier coatings based on zirconium oxide (ZrO2) are used widely in commercial airline, aerospace and power generating engines to raise the safe operating temperatures and improve the lifetimes of metallic components (4, 21, 28, 6, 33). Environmental barrier coatings for non-metallic silicon carbide (SiC), mostly based on refractory silicates, have been the subject of intense development recently, following the realization that lifetimes of SiC components in combustion environments are limited not only by oxidation but also by corrosion from water vapor (29, 25, 26).